The Arizona bark scorpion has the strongest poison of any scorpion in the U.S. But the southern grasshopper mouse just thinks it adds a little punch to lunch.

The southern grasshopper mouse has developed a peculiar reaction to scorpion venom.
(Photo: KQED Science)

The southern grasshopper mouse is an absolutely adorable ball of fluff living in the Sonoran Desert. At least, it's cute to us. To the Arizona bark scorpion, it is an aggressive and deadly predator.

This species of scorpion sends hundreds of people to the hospital every year after delivering an extraordinarily painful sting. In fact, it is the strongest sting of any scorpion species found in the U.S. "Since 2000, three human deaths have been attributed to the Arizona bark scorpion in the United States, all within Arizona," reports KQED.

But the southern grasshopper mouse has come up with a strategy for coping with the sting. Instead of causing long-lasting pain, the scorpion's poison causes a brief discomfort and then numbness. After the first couple stings, the mouse feels no pain and goes in for the kill. This KQED Deep Look video explains the predator-prey relationship:

"The scorpion venom contains neurotoxins that target sodium and potassium ion channels, proteins embedded within the surface of the nerve and muscle cells that play an important role in regulating the sensation of pain," writes KQED. "Activating these channels sends signals down the nerves to the brain...Within the mouse, a special protein in one of the sodium ion channels binds to the scorpion’s neurotoxin. Once bound, the neurotoxin is unable to activate the sodium ion channel and send the pain signal. Instead it has the entirely opposite effect. It shuts down the channel, keeping it from sending any signals, which has a numbing effect for the mouse."

Studying how the southern grasshopper mouse manages to block such a powerful venom has potential benefits for humans. Scientists may be able to model medications after the chemistry used by the mouse, and create pain medications that have no side effects.